Linux terminal octal form of chmod

Question

I want to set a directory to

-rwx r-x r-x 

using the octal form of chmod

what should i type in the terminal after chmod? and how do i calculate the digits in octal form?

Answer 1

It goes like this:

rwx rwx rwx
421 421 421

so what you want is

rwx r-x r-x
421 4-1 4-1
  7   5   5

so you type

chmod 755 nameofdirectory